/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package com.googlecode.bluetools.dom4j.tree;

import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * <p>
 * <code>FilterIterator</code> is an abstract base class which is useful for implementors of {@link Iterator}which
 * filter an existing iterator.
 * </p>
 * 
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.1 $
 * 
 * @deprecated THIS CLASS WILL BE REMOVED IN dom4j-1.6 !!
 */
public abstract class FilterIterator implements Iterator {
	protected Iterator proxy;

	private Object next;

	private boolean first = true;

	public FilterIterator(Iterator proxy) {
		this.proxy = proxy;
	}

	public boolean hasNext() {
		if (first) {
			next = findNext();
			first = false;
		}

		return next != null;
	}

	public Object next() throws NoSuchElementException {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}

		Object answer = this.next;
		this.next = findNext();

		return answer;
	}

	/**
	 * Always throws UnsupportedOperationException as this class does look-ahead with its internal iterator.
	 * 
	 * @throws UnsupportedOperationException always
	 */
	public void remove() {
		throw new UnsupportedOperationException();
	}

	/**
	 * Filter method to perform some matching on the given element.
	 * 
	 * @param element DOCUMENT ME!
	 * 
	 * @return true if the given element matches the filter and should be appear in the iteration
	 */
	protected abstract boolean matches(Object element);

	protected Object findNext() {
		if (proxy != null) {
			while (proxy.hasNext()) {
				Object nextObject = proxy.next();

				if ((nextObject != null) && matches(nextObject)) {
					return nextObject;
				}
			}

			proxy = null;
		}

		return null;
	}
}

/*
 * Redistribution and use of this software and associated documentation ("Software"), with or without modification, are
 * permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and notices. Redistributions must also contain a
 * copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived from this Software without prior written
 * permission of MetaStuff, Ltd. For written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may "DOM4J" appear in their names without prior
 * written permission of MetaStuff, Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
